Multi-lens component used for a LWIR field-integral gas spectral imager

Abstract

This paper reports a miniature multi-lens component used for a LWIR field-integral gas spectral imager. The component is designed for crosstalk minimization and consists of a 4∗3 array of micro-lenses and a detector. To reduce the cost, the detector is uncooled and the optical parameters of the 12 micro-imaging lenses are identical. These include 3.38 mm focal length and 35° field-of-view. The F/# is designed to be 1.2 to increase the luminous flux of the imager. After image quality evaluation and tolerance analysis, the micro-imaging lens has good imaging quality, is insensitive to tolerances, and is easy to fabricate. To enhance the environmental stability of the component, a temperature control system was designed to depress the temperature drift. In addition, the athermalization of the micro-imaging lens was beneficial. The performance test of the component shows that the NETD of the 12 micro-imaging lenses is less than 90 mK and most of them are less than 65 mK, and an image of an ethylene gas cloud observed by the component is also shown. The component has been integrated to the spectral imagers, and crosstalk is analyzed.